The invention relates to a message receiving apparatus that is individually called on a selective basis and a message transmitting and receiving method.
Conventional message receiving apparatuses such as pagers have expanded their calling methods from conventional beeping to message transmission achieved by receiving not only numerals and characters but also graphics data. Such functional expansion sustains a trend toward increased volume of received data.
A conventional message receiving apparatus will be described hereinafter. FIG. 8 shows a construction of a conventional message receiving apparatus. In FIG. 8, reference numeral 81 denotes a receiving section that receives a signal from a transmitting station and outputs a data string by demodulating the signal; and 82, a data processing section that analyzes the data string outputted from the receiving section 81, performs the data string to an error correcting process, makes an address collation, converts the thus processed data string to a message, etc. The data processing section 82 is formed of a decoder 83 that subjects a data string to an error correcting process and makes an address collation and of a buffer 84 that stores a message converted by the decoder 83. Reference numeral 85 denotes a peripheral device section that beeps and displays messages; 86, a total control section that controls reading of messages within the buffer 84, displaying the messages by sending the read messages to the peripheral device section 85, etc.
Then, an operation of the thus constructed message receiving apparatus will be described. First, a signal from a transmitting station is received by the receiving section 81. This signal is, for example, a POCSAG signal currently used for pagers. The receiving section 81 demodulates this signal and converts the demodulated signal into a data string. The decoder 83 receives the data string from the receiving section 81 and subjects the data string to an error correcting process. Generally, a BCH code is used for error correction. If the data is found to be an address, such address is collated with an address specific to the message receiving apparatus. If these addresses are coincident with each other, a message arrival signal is outputted to the total control section 86. The decoder 83 decodes the message by subjecting an inputted data string to an error correcting process and writes the message to the buffer 84. In response to the message arrival signal from the decoder 83, the total control section 86 either displays a message by reading the message stored in the buffer 84 and sending the message to the peripheral device section 85 or beeps by sending a signal indicating the arrival of a message.
However, the aforementioned conventional message receiving apparatus encounters not only circuitry design restrictions for meeting downsizing and low dissipation requirements but also needs for receiving feeble signals as the user moves. Therefore, the operation of the receiving apparatus itself adversely affects the receiving section, thus imposing the problem that bit errors are committed. In particular, as the length of a message is increased, it is highly likely that messages contain errors, and this has imposed the further problem to be solved for accommodating needs for receiving large-volume messages.